Human Body Systems


Key Idea 1: The circulatory system is a closed, one-way system which moves blood throughout the body.

Key Idea 2: Oxygen and nutrients that the body needs are distributed to every cell by the blood. Also, wastes are carried away from every cell by the blood.

Key Idea 3: In the lungs oxygen and carbon dioxide are exchanged between the air and the blood.

Key Idea 4: The digestive system breaks down the pieces of food into molecules that are small enough to be absorbed into the blood.

Key Idea 5: Nutrients, oxygen, carbon dioxide, waste products, and other materials pass in and out of the blood stream by diffusing through the walls of the capillaries.

Key Idea 6: Humans, like all living things, need materials and energy to grow, to maintain and repair themselves, and to carry out life function.